title: The arthritis-associated HLA-B*27:05 allele forms more cell surface B27 dimer and free heavy chain ligands for KIR3DL2 than HLA-B*27:09.
abstract: OBJECTIVE
  HLA-B*27:05 is associated with AS whereas HLA-B*27:09 is not associated. We hypothesized that different interactions with KIR immune receptors could contribute to the difference in disease association between HLA-B*27:05 and HLAB*27:09. Thus, the objective of this study was to compare the formation of β2m-free heavy chain (FHC) including B27 dimers (B272) by HLA-B*27:05 and HLA-B*27:09 and their binding to KIR immunoreceptors.
  
  
  METHODS
  We studied the formation of HLA-B*27:05 and HLA-B*27:09 heterotrimers and FHC forms including dimers in vitro and in transfected cells. We investigated HLA-B*27:05 and HLA-B*27:09 binding to KIR3DL1, KIR3DL2 and LILRB2 by FACS staining with class I tetramers and by quantifying interactions with KIR3DL2CD3ε-reporter cells and KIR3DL2-expressing NK cells. We also measured KIR expression on peripheral blood NK and CD4 T cells from 18 HLA-B*27:05 AS patients, 8 HLA-B27 negative and 12 HLA-B*27:05+ and HLA-B*27:09+ healthy controls by FACS staining.
  
  
  RESULTS
  HLA-B*27:09 formed less B27₂ and FHC than HLA-B*27:05. HLA-B*27:05-expressing cells stimulated KIR3DL2CD3ε-reporter T cells more effectively. Cells expressing HLA-B*27:05 promoted KIR3DL2+ NK cell survival more strongly than HLA-B*27:09. HLA-B*27:05 and HLA-B*27:09 dimer tetramers stained KIR3DL1, KIR3DL2 and LILRB2 equivalently. Increased proportions of NK and CD4 T cells expressed KIR3DL2 in HLA-B*27:05+ AS patients compared with HLA-B*27:05+, HLA-B*27:09+ and HLA-B27- healthy controls.
  
  
  CONCLUSIONS
  Differences in the formation of FHC ligands for KIR3DL2 by HLA-B*27:05 and HLA-B*27:09 could contribute to the differential association of these alleles with AS.
authors.affiliation: Botnar Research Centre, Nuffield Department of Orthopaedics Rheumatology and Musculoskeletal Science, Nuffield Orthopaedic Centre, University of Oxford, Windmill Road, Headington, Oxford OX3 7LD, UK. simon.kollnberger@ndorms.ox.ac.uk.
authors.forename: Alberto
authors.initials: A
authors.lastname: Cauli
authors.forename: Jacqueline
authors.initials: J
authors.lastname: Shaw
authors.forename: Joanna
authors.initials: J
authors.lastname: Giles
authors.forename: Hiroko
authors.initials: H
authors.lastname: Hatano
authors.forename: Oliwia
authors.initials: O
authors.lastname: Rysnik
authors.forename: Sravan
authors.initials: S
authors.lastname: Payeli
authors.forename: Kirsty
authors.initials: K
authors.lastname: McHugh
authors.forename: Grazia
authors.initials: G
authors.lastname: Dessole
authors.forename: Giovanni
authors.initials: G
authors.lastname: Porru
authors.forename: Elisabetta
authors.initials: E
authors.lastname: Desogus
authors.forename: Sarah
authors.initials: S
authors.lastname: Fiedler
authors.forename: Soraya
authors.initials: S
authors.lastname: Hölper
authors.forename: Amanda
authors.initials: A
authors.lastname: Carette
authors.forename: Miguel Angel
authors.initials: MA
authors.lastname: Blanco-Gelaz
authors.forename: Alessandra
authors.initials: A
authors.lastname: Vacca
authors.forename: Matteo
authors.initials: M
authors.lastname: Piga
authors.forename: Valentina
authors.initials: V
authors.lastname: Ibba
authors.forename: Pietro
authors.initials: P
authors.lastname: Garau
authors.forename: Giorgio
authors.initials: G
authors.lastname: La Nasa
authors.forename: Carlos
authors.initials: C
authors.lastname: López-Larrea
authors.forename: Alessandro
authors.initials: A
authors.lastname: Mathieu
authors.forename: Christoph
authors.initials: C
authors.lastname: Renner
authors.forename: Paul
authors.initials: P
authors.lastname: Bowness
authors.forename: Simon
authors.initials: S
authors.lastname: Kollnberger
mesh_terms: D000328:Adult; D000483:Alleles; D015496:CD4-Positive T-Lymphocytes / Q000276:immunology; D002470:Cell Survival / Q000276:immunology; D002478:Cells, Cultured; D018920:Coculture Techniques; D005260:Female; D020022:Genetic Predisposition to Disease; D015796:HLA-B27 Antigen / Q000235:genetics / Q000378:metabolism*; D006801:Humans; D007143:Immunoglobulin Heavy Chains / Q000378:metabolism*; D007694:Killer Cells, Natural / Q000276:immunology; D008024:Ligands; D008297:Male; D008875:Middle Aged; D054347:Receptors, KIR3DL2 / Q000378:metabolism*; D013167:Spondylitis, Ankylosing / Q000235:genetics* / Q000276:immunology / Q000378:metabolism; D014162:Transfection
chemical_list: C464936:HLA-B*27:05 antigen; C464937:HLA-B*27:09 antigen; D015796:HLA-B27 Antigen; D007143:Immunoglobulin Heavy Chains; C515084:KIR3DL2 protein, human; D008024:Ligands; D054347:Receptors, KIR3DL2
keywords: B27 homodimer; HLA-B*27:05; HLA-B*27:09; KIR3DL1; KIR3DL2; spondyloarthritis